<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        'use strict';
        fn();
        function fn(){
            console.log(this);
            
        }
    </script>
    <!-- <script>
        (function () {
            'use strict';
        })()
    </script> -->
</body>

</html>